Plating method, plating apparatus and recording medium

ABSTRACT

A substrate W having a non-plateable material portion  31  and a plateable material portion  32  formed on a surface thereof is prepared, and then, a catalyst is imparted selectively to the plateable material portion  32  by supplying a catalyst solution N 1  onto the substrate W. Thereafter, a plating layer  35  is selectively formed on the plateable material portion  32  by supplying a plating liquid M 1  onto the substrate W. A pH of the catalyst solution N 1  is previously adjusted such that the plating layer  35  is suppressed from being precipitated on the non-plateable material portion  31  while being facilitated to be precipitated on the plateable material portion  32.

TECHNICAL FIELD

The various aspects and embodiments described herein pertain generallyto a plating method, a plating apparatus and a recording medium.

BACKGROUND

Recently, as miniaturization and three-dimension of semiconductordevices are required, it is required to improve processing accuracy byetching when processing the semiconductor devices. As one way to improvethe processing accuracy by etching, it is required to improve accuracyof a hard mask (HM) for dry etching which is formed on a substrate.

Patent Document 1: Japanese Patent Laid-open Publication No. 2009-249679

In general, however, there are many restrictions for a material of thehard mask. For example, the material of the hard mask needs to have highadhesivity to a substrate and a resist, needs to have high resistanceagainst a heat treatment, and an etching processing, and, also, needs tobe easily removed. For the reason, conventionally, only a limitedmaterial such as SiN (silicon nitride) or TiN (titanium nitride) hasbeen used as the material of the hard mask.

In view of this, the present inventors have examined providing a film ofSiO₂ (silicon oxide) or the like and a film of SiN (silicon nitride) orthe like on a substrate; applying a catalyst such as Pd on the substrateto selectively apply the catalyst on the SiN film; and forming a platinglayer only on the SiN film by using this catalyst. In this case, as theplating layer formed on the SiN film can be used as the hard mask, it ispossible to select various kinds of materials as the plating layer.

In the process of imparting the catalyst such as Pd, however, thecatalyst uniformly adheres not only to the SiN film but also to the SiOfilm where the plating layer is not intended to be formed. In this case,adhesivity between the catalyst and the SiO film is weaker thanadhesivity between the catalyst and the SiN film. Accordingly, thecatalyst is separated from the SiO film by the time when a platingprocessing is performed, and, as a result, the catalyst is impartedselectively only to the SiN film.

In case of using a conventional method, however, it has been difficultto perform a processing on improvement of the adhesivity between thecatalyst and the SiN film after the catalyst is imparted and beforeperforming the plating processing. That is, if the processing on theimprovement of the adhesivity between the catalyst and the SiN film isperformed, the adhesivity between the catalyst and the SiO film is alsoimproved.

SUMMARY

In view of the foregoing, exemplary embodiments provide a platingmethod, a plating apparatus capable of allowing, when imparting acatalyst, the catalyst to be attached selectively to a plateablematerial portion from the beginning, and a recording medium therefor.

In an exemplary embodiment, a plating method includes preparing asubstrate having a non-plateable material portion and a plateablematerial portion formed on a surface thereof; imparting a catalystselectively to the plateable material portion by supplying a catalystsolution onto the substrate; and forming a plating layer selectively onthe plateable material portion by supplying a plating liquid onto thesubstrate. A pH of the catalyst solution is previously adjusted suchthat the plating layer is suppressed from being precipitated on thenon-plateable material portion while being facilitated to beprecipitated on the plateable material portion.

In another exemplary embodiment, a plating apparatus includes asubstrate holding unit configured to hold a substrate having a plateablematerial portion and a non-plateable material portion on a surfacethereof; a catalyst imparting unit configured to impart a catalystselectively to the plateable material portion by supplying a catalystsolution onto the substrate; and a plating liquid supply unit configuredto form a plating layer selectively on the plateable material portion bysupplying a plating liquid onto the substrate. A pH of the catalystsolution is previously adjusted such that the plating layer issuppressed from being precipitated on the non-plateable material portionwhile being facilitated to be precipitated on the plateable materialportion.

According to the exemplary embodiments as stated above, in the processof imparting the catalyst, the catalyst can be selectively attached tothe plateable material portion from the beginning.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view illustrating a configuration of aplating apparatus and a plating unit provided in the plating apparatus.

FIG. 2 is a schematic cross sectional view illustrating a configurationof a plating device belonging to the plating unit shown in FIG. 1.

FIG. 3 is a schematic cross sectional view illustrating a structure of asubstrate on which a plating layer is to be formed by a plating methodaccording to an exemplary embodiment.

FIG. 4A to FIG. 4E are schematic cross sectional views illustrating amanufacturing method for a substrate on which the plating layer is to beformed by the plating method according to the present exemplaryembodiment.

FIG. 5 is a flowchart illustrating the plating method according to theexemplary embodiment.

FIG. 6A to FIG. 6B are schematic cross sectional views illustrating theplating method according to the exemplary embodiment.

FIG. 7A to FIG. 7C are schematic cross sectional views illustrating amethod of processing the substrate on which the plating layer is formedby the plating method according to the present exemplary embodiment.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments will be explained with reference tothe accompanying drawings.

<Configuration of Plating Apparatus>

Referring to FIG. 1, a configuration of a plating apparatus according toan exemplary embodiment will be explained. FIG. 1 is a schematic diagramillustrating the configuration of the plating apparatus according to theexemplary embodiment.

As depicted in FIG. 1, a plating apparatus 1 according to the presentexemplary embodiment is equipped with a plating unit 2 and a controller3 configured to control an operation of the plating unit 2.

The plating unit 2 is configured to perform various processings on asubstrate. The various processings performed by the plating unit 2 willbe discussed later.

The controller 3 is implemented by, for example, a computer, andincludes an operation controller and a storage unit. The operationcontroller is implemented by, for example, a CPU (Central ProcessingUnit) and is configured to control an operation of the plating unit 2 byreading and executing the programs stored in the storage unit. Thestorage unit is implemented by a memory device such as, but not limitedto, a RAM (Random Access Memory), a ROM (Read Only Memory) or a harddisk, and stores thereon programs for controlling various processingsperformed in the plating unit 2. Further, the programs may be recordedin a computer-readable recording medium, or may be installed from therecording medium to the storage unit. The computer-readable recordingmedium may be, for example, a hard disc (HD), a flexible disc (FD), acompact disc (CD), a magnet optical disc (MO), or a memory card. Storedin the recording medium is a program which, when executed by a computerfor controlling an operation of the plating apparatus 1, allows thecomputer to control the plating apparatus 1 to perform a plating methodto be described later.

<Configuration of Plating Unit>

Referring to FIG. 1, a configuration of the plating unit 2 will bediscussed. FIG. 1 is a schematic plan view illustrating theconfiguration of the plating unit 2.

The plating unit 2 includes a carry-in/out station 21 and a processingstation 22 which is provided adjacent to the carry-in/out station 21.

The carry-in/out station 21 is equipped with a placing section 211 and atransfer section 212 which is provided adjacent to the placing section211.

In the placing section 211, transfer containers (hereinafter, referredto as “carriers C”) for accommodating therein a plurality of substratesW horizontally are placed.

The transfer section 212 is equipped with a transfer device 213 and adelivery unit 214. The transfer device 213 is provided with a holdingmechanism configured to hold a substrate W and is configured to bemovable horizontally and vertically and pivotable around a verticalaxis.

The processing station 22 includes plating devices 5. In the presentexemplary embodiment, the number of the plating devices 5 belonging tothe processing station 22 is two or more. However, only one platingdevice 5 may be provided. The plating devices 5 are arranged at bothsides of a transfer path 221 which is extended in a preset direction.

A transfer device 222 is provided in the transfer path 221. The transferdevice 222 is equipped with a holding mechanism configured to hold thesubstrate W and is configured to be movable horizontally and verticallyand pivotable around a vertical axis.

In the plating unit 2, the transfer device 213 of the carry-in/outstation 21 is configured to transfer the substrate W between the carrierC and the delivery unit 214. To elaborate, the transfer device 213 takesout the substrate W from the carrier C which is placed in the placingsection 211, and places the substrate W in the delivery unit 214.Further, the transfer device 213 takes out the substrate W which isplaced in the delivery unit 214 by the transfer device 222 of theprocessing station 22, and accommodates the substrate W back into thecarrier C on the placing section 211.

In the plating unit 2, the transfer device 222 of the processing station22 is configured to transfer the substrate W between the delivery unit214 and the plating device 5 and between the plating device 5 and thedelivery unit 214. To elaborate, the transfer device 222 takes out thesubstrate W which is placed in the delivery unit 214 and then carriesthe substrate W into the plating device 5. Further, the transfer device222 takes out the substrate W from the plating device 5 and places thesubstrate W in the delivery unit 214.

<Configuration of Plating Device>

Referring to FIG. 2, a configuration of the plating device 5 will beexplained. FIG. 2 is a schematic cross sectional view illustrating theconfiguration of the plating device 5.

The plating device 5 is configured to perform a plating processing on asubstrate W having a non-plateable material portion 31 and a plateablematerial portion 32 on a surface thereof, and configured to form aplating layer 35 selectively on the plateable material portion (see FIG.3 to FIG. 7D to be described later). A substrate processing performed bythe plating device 5 includes a catalyst imparting processing and anelectroless plating processing at least. However, the substrateprocessing may further include processings other than the catalystimparting processing and the plating processing.

The plating device 5 is configured to perform a substrate processingincluding the aforementioned electroless plating processing. The platingdevice 5 includes a chamber 51; a substrate holding unit 52 providedwithin the chamber 51 and configured to hold the substrate W; and aplating liquid supply unit 53 configured to supply a plating liquid M1to the substrate W held by the substrate holding unit 52.

The substrate holding unit 52 includes a rotation shaft 521 extended ina vertical direction within the chamber 51; a turntable 522 provided atan upper end portion of the rotation shaft 521; a chuck 523 provided onan outer peripheral portion of a top surface of the turntable 522 andconfigured to support an edge portion of the substrate W; and a drivingunit 524 configured to rotate the rotation shaft 521.

The substrate W is supported by the chuck 523 to be horizontally held bythe turntable 522 while being slightly spaced apart from the top surfaceof the turntable 522. In the present exemplary embodiment, a mechanismof holding the substrate W by the substrate holding unit 52 is of aso-called mechanical chuck type in which the edge portion of thesubstrate W is held by the chuck 523 which is configured to be movable.However, a so-called vacuum chuck type of vacuum-attracting a rearsurface of the substrate W may be used instead.

A base end portion of the rotation shaft 521 is rotatably supported bythe driving unit 524, and a leading end portion of the rotation shaft521 sustains the turntable 522 horizontally. If the rotation shaft 521is rotated, the turntable 522 placed on the upper end portion of therotation shaft 521 is rotated, and, as a result, the substrate W whichis held by the turntable 522 with the chuck 523 is also rotated.

The plating liquid supply unit 53 is equipped with a nozzle 531configured to discharge the plating liquid M1 onto the substrate W heldby the substrate holding unit 52; and a plating liquid supply source 532configured to supply the plating liquid M1 to the nozzle 531. Theplating liquid M1 is stored in a tank of the plating liquid supplysource 532, and the plating liquid M1 is supplied into the nozzle 531from the plating liquid supply source 532 through a supply passageway534 which is equipped with a flow rate controller such as a valve 533.

The plating liquid M1 is an autocatalytic (reduction) plating liquid forelectroless plating. The plating liquid M1 contains a metal ion such asa cobalt (Co) ion, a nickel (Ni) ion, a tungsten (W) ion; and a reducingagent such as hypophosphorous acid or dimethylamineborane. Further, inthe autocatalytic (reduction) electroless plating, the metal ion in theplating liquid M1 is reduced by the electrons emitted in an oxidationreaction of the reducing agent in the plating liquid M1 to beprecipitated as a metal, so that a metal film (plating film) is formed.The plating liquid M1 may further contain an additive or the like. Themetal film (plating film) formed by the plating processing with theplating liquid M1 may be, by way of non-limiting example, CoB, CoP,CoWP, CoWB, CoWBP, NiWB, NiB, NiWP, NiWBP, or the like. P in the metalfilm (plating film) is originated from the reducing agent (e.g.,hypophosphorous acid) containing P, and B in the plating film isoriginated from the reducing agent (e.g., dimethylamineborane)containing B.

The nozzle 531 is connected to a nozzle moving device 54. The nozzlemoving device 54 is configured to drive the nozzle 531. The nozzlemoving device 54 includes an arm 541, a moving body 542 which isconfigured to be movable along the arm 541 and has a driving mechanismembedded therein; and a rotating/elevating device 543 configured torotate and move the arm 541 up and down. The nozzle 531 is provided atthe moving body 542. The nozzle moving device 54 is capable of movingthe nozzle 531 between a position above a center of the substrate W heldby the substrate holding unit 52 and a position above a periphery of thesubstrate W, and is also capable of moving the nozzle 531 up to astand-by position outside a cup 57 to be described later when viewedfrom the top.

Within the chamber 51, there are arranged a catalyst solution supplyunit (catalyst imparting unit) 55 a, a cleaning liquid supply unit 55 band a rinse liquid supply unit 55 c configured to supply a catalystsolution N1, a cleaning liquid N2 and a rinse liquid N3 onto thesubstrate W held by the substrate holding unit 52, respectively.

The catalyst solution supply unit (catalyst imparting unit) 55 aincludes a nozzle 551 a configured to discharge the catalyst solution N1onto the substrate W held by the substrate holding unit 52; and acatalyst solution supply source 552 a configured to supply the catalystsolution N1 to the nozzle 551 a. The catalyst solution N1 is stored in atank of the catalyst solution supply source 552 a, and the catalystsolution N1 is supplied to the nozzle 551 a from the catalyst solutionsupply source 552 a through a supply passageway 554 a which is providedwith a flow rate controller such as a valve 553 a.

The cleaning liquid supply unit 55 b includes a nozzle 551 b configuredto discharge the cleaning liquid N2 onto the substrate W held by thesubstrate holding unit 52; and a cleaning liquid supply source 552 bconfigured to supply the cleaning liquid N2 to the nozzle 551 b. Thecleaning liquid N2 is stored in a tank of the cleaning liquid supplysource 552 b, and the cleaning liquid N2 is supplied to the nozzle 551 bfrom the cleaning liquid supply source 552 b through a supply passageway554 b which is provided with a flow rate controller such as a valve 553b.

The rinse liquid supply unit 55 c includes a nozzle 551 c configured todischarge the rinse liquid N3 onto the substrate W held by the substrateholding unit 52; and a rinse liquid supply source 552 c configured tosupply the rinse liquid N3 to the nozzle 551 c. The rinse liquid N3 isstored in a tank of the rinse liquid supply source 552 c, and the rinseliquid N3 is supplied to the nozzle 551 c from the rinse liquid supplysource 552 c through a supply passageway 554 c which is provided with aflow rate controller such as a valve 553 c.

The catalyst solution N1 contains a metal ion having catalytic activityto the oxidation reaction of the reducing agent in the plating liquidM1. In the electroless plating processing, in order for precipitation ofthe metal ion in the plating liquid M1 to be started, an initial filmsurface (that is, a plating target surface of the substrate) needs tohave sufficient catalytic activity to the oxidation reaction of thereducing agent in the plating liquid M1. As an example, such a catalystmay include, by way of example, but not limitation, an iron groupelement (Fe, Co, Ni), a platinum metal element (Ru, Rh, Pd, Os, Ir, Pt),Cu, Ag or Au. The metal film having the catalytic activity is formedthrough a replacement reaction. In the replacement reaction, a componentforming the plating target surface of the substrate serves as thereducing agent, and the metal ion (e.g., Pd ion) in the catalystsolution N1 is reduced to be precipitated on the plating target surfaceof the substrate. Further, the catalyst solution N1 may contain a metalcatalyst in the form of nanoparticles. To be more specific, the catalystsolution N1 may contain a metal catalyst in the form of nanoparticles, adispersant and an aqueous solution. The metal catalyst in the form ofnanoparticles may be, by way of non-limiting example,nanoparticle-shaped palladium (Pd). Further, the dispersant serves toallow the metal catalyst in the form of nanoparticles to be easilydispersed in the catalyst solution N1. The dispersant may be, by way ofnon-limiting example, polyvinylpyrrolidone (PVP).

In the present exemplary embodiment, a pH of the catalyst solution N1 ispreviously adjusted such that a plating layer 35 (to be described later)is suppressed from being precipitated on the non-plateable materialportion 31 of the substrate W while being facilitated to be precipitatedon the plateable material portion 32. To elaborate, in case that thenon-plateable material portion 31 is made of a material having SiO₂ as amain component and the plateable material portion 32 is made of amaterial having SiN as a main component, the pH of the catalyst solutionN1 is adjusted to be in a range from 2 to 3. In general, the pH of thecatalyst solution N1 before the adjustment ranges from 4 to 6.Therefore, acidity of the catalyst solution N1 is increased than aciditybefore the adjustment. Further, the pH adjustment of the catalystsolution N1 may be performed by adding a pH adjuster such as sulfuricacid (H₂SO₄) or tetramethylammonium hydroxide (TMAH), or, hydrochloricacid (HCl₂) or ammonia water (NH₄OH) into the catalyst solution N1within a tank of the plating liquid supply source 532 and adjusting anamount of this pH adjuster.

As an example of the cleaning liquid N2, an organic acid such as aformic acid, malic acid, a succinic acid, a citric acid or a malonicacid, or hydrofluoric acid (DHF) (aqueous solution of hydrogen fluoride)diluted to the extent that it does not corrode the plating targetsurface of the substrate may be used.

As an example of the rinse liquid N3, pure water may be used.

The plating device 5 includes a nozzle moving device 56 configured tomove the nozzles 551 a to 551 c. The nozzle moving device 56 is equippedwith an arm 561; a moving body 562 which is configured to be movablealong the arm 561 and has a moving mechanism embedded therein; and arotating/elevating device 563 configured to rotate and move the arm 561up and down. The nozzles 551 a to 551 c are provided at the moving body562. The nozzle moving device 56 is capable of moving the nozzles 551 ato 551 c between a position above the central portion of the substrate Wheld by the substrate holding unit 52 and a position above theperipheral portion of the substrate W, and also capable of moving thenozzles 551 a to 551 c up to a stand-by position outside the cup 57 tobe described later when viewed from the top. In the present exemplaryembodiment, though the nozzles 551 a to 551 c are held by the commonarm, they may be configured to be held by different arms and movedindependently.

The cup 57 is disposed around the substrate holding unit 52. The cup 57is configured to receive various kinds of processing liquids (e.g., theplating liquid, the cleaning liquid, the rinse liquid, etc.) scatteredfrom the substrate W and drain the received processing liquids to theoutside of the chamber 51. The cup 57 is equipped with an elevatingdevice 58 configured to move the cup 57 up and down.

<Structure of Substrate>

Now, a structure of the substrate in which a plating layer is to beformed by a plating method according to the present exemplary embodimentwill be explained.

As depicted in FIG. 3, a substrate W on which a plating layer 35 is tobe formed includes the non-plateable material portion 31 and theplateable material portion 32 respectively formed on a surface thereof.There is no specific limitation in the structure of the non-plateablematerial portion 31 and the plateable material portion 32 as long asthey are exposed at the surface side of the substrate W. In the presentexemplary embodiment, the substrate W includes a base member 42 made ofthe plateable material portion 32 and a core member 41 which isprotruded from the base member 42 and is made of the non-plateablematerial portion 31 having a pattern shape.

The non-plateable material portion 31 is a region where a plating metalis not precipitated so that the plating layer 35 is not formed when aplating processing according to the present exemplary embodiment isperformed. In the present exemplary embodiment, the non-plateablematerial portion 31 is made of a material containing SiO₂ as a maincomponent. Further, as will be described later, the non-plateablematerial portion 31 may include a minute lattice defect, an impurity, orthe like.

The plateable material portion 32 is a region where the plating metal isselectively precipitated so that the plating layer 35 is formed when theplating processing according to the present exemplary embodiment isperformed. In the present exemplary embodiment, the plateable materialportion 32 may be made of any one of (1) a material containing at leastone of a OCH_(x) group or a NH_(x) group; (2) a metal materialcontaining a Si-based material as a main component; (3) a materialcontaining a catalyst metal material as a main component; and (4) amaterial containing carbon as a main component.

(1) In case that the material of the plateable material portion 32includes, as the main component, the material containing at least one ofthe OCH_(x) group or the NH_(x) group, this material may be a materialcontaining a Si—OCH_(x) group or a Si—NH_(x) group such as SiOCH or SiN.

(2) In case that the material of the plateable material portion 32 isthe metal material containing the Si-based material as the maincomponent, the material of the plateable material portion 32 may be, byway of non-limiting example, B-doped or P-doped poly-Si, poly-Si or Si.

(3) In case that the plateable material portion 32 includes, as the maincomponent, the material containing the catalyst metal material as themain component, the material of the plateable material portion 32 maybe, by way of example, but not limitation, Cu or Pt.

(4) In case that the plateable material portion 32 includes, as the maincomponent, the material containing the carbon as the main component, thematerial of the plateable material portion 32 may be, for example,amorphous carbon.

Now, a method of fabricating the substrate W shown in FIG. 3 will beexplained with reference to FIG. 4A to FIG. 4E. To produce the substrateW shown in FIG. 3, the base member 42 made of the plateable materialportion 32 is first prepared, as illustrated in FIG. 4A.

Thereafter, as depicted in FIG. 4B, a film of a material 31 a, whichforms the non-plateable material portion 31, is formed on the entiresurface of the base member 42 made of the plateable material portion 32by a CVD method, a PVD method or the like. The material 31 a is composedof, for example, the material containing SiO₂ as the main component.

Subsequently, as illustrated in FIG. 4C, a photosensitive resist 33 a iscoated on the entire surface of the material 31 a forming thenon-plateable material portion 31 and is dried. Then, by exposing thephotosensitive resist 33 a through a photo mask and developing it, aresist film 33 having a required pattern is formed, as shown in FIG. 4D.

Afterwards, as depicted in FIG. 4E, the material 31 a is dry-etched byusing the resist film 33 as a mask. As a result, the core member 41 madeof the non-plateable material portion 31 is patterned to havesubstantially the same shape as the pattern shape of the resist film 33.Then, by removing the resist film 33, there is obtained the substrate Whaving the non-plateable material portion 31 and the plateable materialportion 32 formed on the surface thereof.

<Plating Method>

Now, a plating method using the plating apparatus 1 will be discussed.The plating method performed by plating apparatus 1 includes a platingprocessing upon the aforementioned substrate W. The plating processingis performed by the plating device 5. An operation of the plating device5 is controlled by the controller 3.

First, the substrate W having the non-plateable material portion 31 andthe plateable material portion 32 formed on the surface thereof isprepared by performing the above-described method of FIG. 4A to FIG. 4E(preparation process: process S1 of FIG. 5) (see FIG. 6A).

The prepared substrate W is then carried into the plating device 5 andis held by the substrate holding unit 52 (see FIG. 2). In the meanwhile,the controller 3 controls the elevating device 58 to move the cup 57down to a preset position. Then, the controller 3 controls the transferdevice 222 to place the substrate W on the substrate holding unit 52.The substrate W is horizontally placed on the turntable 522 while itsperiphery portion is held by the chuck 523.

Then, the substrate W held by the substrate holding unit 52 is cleaned(pre-cleaning process: process S2 of FIG. 5). At this time, whilecontrolling the driving unit 524 to rotate the substrate W held by thesubstrate holding unit 52 at a preset speed, the controller 3 controlsthe cleaning liquid supply unit 55 b to locate the nozzle 551 b at aposition above the substrate W and to supply the cleaning liquid N2 ontothe substrate W from the nozzle 551 b. The cleaning liquid N2 suppliedonto the substrate W is diffused on the surface of the substrate W by acentrifugal force which is caused by the rotation of the substrate W. Asa result, a deposit or the like adhering to the substrate W is removedfrom the substrate W. The cleaning liquid N2 scattered from thesubstrate W is drained through the cup 57.

Subsequently, the substrate W after being cleaned is rinsed (rinsingprocess: process S3 of FIG. 5). At this time, while controlling thedriving unit 524 to rotate the substrate W held by the substrate holdingunit 52 at a preset speed, the controller 3 controls the rinse liquidsupply unit 55 c to locate the nozzle 551 c at a position above thesubstrate W and to supply the rinse liquid N3 onto the substrate W fromthe nozzle 551 c. The rinse liquid N3 supplied onto the substrate W isdiffused on the surface of the substrate W by the centrifugal forcewhich is caused by the rotation of the substrate W. As a result, thecleaning liquid N2 remaining on the substrate W is washed away. Therinse liquid N3 scattered from the substrate W is drained through thecup 57.

Thereafter, a catalyst imparting processing is performed on thesubstrate W (catalyst imparting process: process S4 of FIG. 5). At thistime, while controlling the driving unit 524 to rotate the substrate Wheld by the substrate holding unit 52 at a preset speed, the controller3 controls the catalyst solution supply unit 55 a to locate the nozzle551 a at a position above the substrate W and to supply the catalystsolution N1 onto the substrate W from the nozzle 551 a. The catalystsolution N1 supplied onto the substrate W is diffused on the surface ofthe substrate W by the centrifugal force which is caused by the rotationof the substrate W. The catalyst solution N1 scattered from thesubstrate W is drained through the cup 57.

In the present exemplary embodiment, the pH of the catalyst solution N1is previously adjusted (catalyst solution pH adjustment process: processS8 of FIG. 5). To be specific, the pH of the catalyst solution N1 isadjusted such that the plating layer 35 is suppressed from beingprecipitated on the non-plateable material portion 31 while beingfacilitated to be precipitated on the plateable material portion 32. Byway of example, in case that the non-plateable material portion 31 ismainly made of SiO₂ and the plateable material portion 32 is mainly madeof SiN, the pH of the catalyst solution N1 is adjusted to be in a rangefrom 2 to 3. Accordingly, in the catalyst imparting process (process S4of FIG. 5), the catalyst such as Pd is allowed to easily adhere to theplateable material portion 32 without being attached to thenon-plateable material portion 31. Thus, until the plating process(process S5 of FIG. 5) is performed after the catalyst imparting process(process S4 of FIG. 5), it is possible to perform a processing (forexample, a heat treatment) for improving the adhesivity between thecatalyst and the plateable material portion 32.

Accordingly, the catalyst is selectively imparted to the plateablematerial portion 32 of the substrate W, so that the metal film havingcatalytic activity is formed on the plateable material portion 32.Meanwhile, the catalyst is not substantially imparted to thenon-plateable material portion 31 of the substrate W, which is mainlymade of SiO₂, so that the metal film having the catalytic activity isnot formed at this non-plateable material portion 31. By way of example,the metal having such catalytic activity may include, but notlimitation, an iron group element (Fe, Co, Ni), a platinum metal element(Ru, Rh, Pd, Os, Ir, Pt), Cu, Ag or Au. Each of these metals have highadsorption property to the material (e.g., SiN) forming the plateablematerial portion 32, whereas each of these metals is difficult to adsorbwith respect to the material (e.g., SiO₂) forming the non-plateablematerial portion 31. Further, as stated above, the pH of the catalystsolution N1 is previously adjusted such that the plating layer 35 issuppressed from being precipitated on the non-plateable material portion31 while being facilitated to be precipitated on the plateable materialportion 32. Thus, a plating metal can be selectively precipitated on theplateable material portion 32. The catalyst solution N1 may contain thePd catalyst in the form of nanoparticles, the dispersant composed ofpolyvinylpyrrolidone (PVP), and the aqueous solution. Further, thecatalyst solution N1 may contain an adsorption promoter which promotesthe adsorption of the metal having the catalytic activity.

Then, the plating processing is performed on the substrate W, and theplating is selectively performed on the plateable material portion 32(plating process: process S5 of FIG. 5). Resultantly, the plating layer35 is formed on the plateable material portion 32 (see FIG. 6B). Theplating layer 35 is formed at a portion of the plateable materialportion 32 where the non-plateable material portion 31 is not covered.At this time, while controlling the driving unit 524 to rotate thesubstrate W held by the substrate holding unit 52 at a preset speed orwhile maintaining the substrate W held by the substrate holding unit 52stopped, the controller 3 controls the plating liquid supply unit 53 tolocate the nozzle 531 at a position above the substrate W and to supplythe plating liquid M1 onto the substrate W from the nozzle 531.Accordingly, the plating metal is selectively precipitated on theplateable material portion 32 (specifically, on the metal film, havingthe catalytic activity, formed on the surface of the plateable materialportion 32) of the substrate W, so that the plating layer 35 isobtained. Meanwhile, since the catalyst is not substantially imparted tothe non-plateable material portion 31 of the substrate W as statedabove, the metal film having the catalytic activity is not formed on thenon-plateable material portion 31. As a result, the plating metal is notsubstantially precipitated on the non-plateable material portion 31 andno plating layer 35 is formed thereon.

After the plating processing as described above is completed, thesubstrate W held by the substrate holding unit 52 is cleaned(post-cleaning process: process S6 of FIG. 5). At this time, whilecontrolling the driving unit 524 to rotate the substrate W held by thesubstrate holding unit 52 at a preset speed, the controller 3 controlsthe cleaning liquid supply unit 55 b to locate the nozzle 551 b at theposition above the substrate W and to supply the cleaning liquid N2 ontothe substrate W from the nozzle 551 b. The cleaning liquid N2 suppliedonto the substrate W is diffused on the surface of the substrate W bythe centrifugal force which is caused by the rotation of the substrateW. Accordingly, the abnormal plating film or the reaction by-productadhering to the substrate W is removed from the substrate W. Thecleaning liquid N2 scattered from the substrate W is drained through thecup 57.

Then, while controlling the driving unit 524 to rotate the substrate Wheld by the substrate holding unit 52 at a preset speed, the controller3 controls the rinse liquid supply unit 55 c to locate the nozzle 551 cat the position above the substrate W and to supply the rinse liquid N3onto the substrate W from the nozzle 551 c (rinsing process: process S7of FIG. 5). Accordingly, the plating liquid Ml, the cleaning liquid N2and the rinse liquid N3 on the substrate W are scattered from thesubstrate W by the centrifugal force which is caused by the rotation ofthe substrate W, and are drained through the cup 57.

Thereafter, the substrate W on which the plating layer 35 is formed iscarried out of the plating device 5. At this time, the controller 3controls the transfer device 222 to take out the substrate W from theplating device 5 and place the taken-out substrate W in the deliveryunit 214. Then, the controller 3 controls the transfer device 213 totake out the substrate W placed in the delivery unit 214 and to carrythe substrate W into the carrier C in the placing section 211.

Then, the substrate W is etched by using the plating layer 35 as a hardmask layer.

In this case, the non-plateable material portion 31 is first removedselectively from the substrate W which is taken out of the platingdevice 5 (FIG. 7A). Meanwhile, the plating layer 35 formed on theplateable material portion 32 remains without being removed.

Subsequently, as shown in FIG. 7B, the base member 42 made of theplateable material portion 32 is dry-etched by using the plating layer35 as a hard mask. Accordingly, the portion of the base member 42 whichis not covered with the plating layer 35 is etched to a preset depth,and recesses having a pattern shape are formed.

Afterwards, by removing the plating layer 35 through a wet cleaningmethod, the base member 42 provided with the recesses having the patternshape is obtained, as illustrated in FIG. 7C. Since the plating layer 35can be removed by the wet cleaning method, it is easy to remove theplating layer 35. An acidic solvent is employed as a chemical liquid forthis wet cleaning method.

As stated above, according to the present exemplary embodiment, in theprocess of imparting the catalyst such as Pd, the pH of the catalystsolution N1 is previously adjusted such that the plating layer 35 issuppressed from being precipitated on the non-plateable material portion31 while being facilitated to be precipitated on the plateable materialportion 32. Accordingly, the catalyst in the catalyst solution N1 doesnot adhere to the non-plateable material portion 31 but selectivelyadheres to the plateable material portion 32 from the beginning. In thiscase, after the catalyst imparting process (process S4 of FIG. 5) andbefore the plating process (process S5 of FIG. 5), it is possible toperform a processing of improving the adhesivity between the catalystand the plateable material portion 32.

The reason why the catalyst in the catalyst solution N1 can beselectively attached to the plateable material portion 32 by adjustingthe pH of the catalyst solution N1 is deemed to be as follows. That is,the non-plateable material portion 31 and the plateable material portion32 of the substrate W have different surface potentials and differentisoelectric points. In the catalyst imparting process, electric chargesin the surface of the substrate W change depending on the pH of thecatalyst solution N1. By way of example, the SiO₂ forming thenon-plateable material portion 31 and the SiN forming the plateablematerial portion 32 tend to show the same pH dependency. That is, inboth the SiO₂ and the SiN, each of the electric charges change fromnegative to positive as the pH of the catalyst solution N1 changes fromthe alkali toward the acid. Since, however, the isoelectric points ofthe SiO₂ and the SiN are different, the electric charges of the SiO₂ andthe SiN become opposite in a certain pH range. That is, in a pH rangebetween the isoelectric points of the SiO₂ and the SiN, the electriccharges of the SiO₂ and the SiN have the opposite polarities. Since theisoelectric point of the SiO₂ is located at a more acidic side than theisoelectric point of the SiN, the electric charges of the SiO₂ becomenegative whereas the electric charges of the SiN become positive in thepH range between the isoelectric points of the SiO₂ and the SiN. This pHrange is approximately a range from pH 2 to pH 3. In this range, if acatalyst metal particle having a negative electric charge is used, it iselectrically attracted to the SiN which is positively charged, so thatthe catalyst metal particle can be easily attached to the SiN.Meanwhile, the catalyst metal particle having the negative charge iselectrically repellent against the SiO₂ which is negatively charged.Thus, the catalyst metal particle is difficult to attach to the SiO₂.For this reason, by adjusting the pH of the catalyst solution N1 to bein the pH range between the isoelectric points of the SiO₂ and the SiN,it is possible to allow the catalyst in the catalyst solution N1 toadhere to the SiN selectively from the beginning. Desirably, by using apH range where the catalyst metal particle is most negatively charged,the best effect can be achieved.

Further, according to the present exemplary, even if a minute impurity(or lattice defect) exists on the part of the non-plateable materialportion 31, the adsorption of the catalyst to this impurity issuppressed. Accordingly, in the plating process, the metal particle M inthe plating liquid M1 can be suppressed from being adsorbed to theimpurity on the non-plateable material portion 31, so that the growth ofthe plating layer 35 from the catalyst on the impurity is suppressed. Asa result, after the plating processing, the plating layer is not formedon the non-plateable material portion 31 where the plating layer is notintended to be formed, so that the generation of the defect on thenon-plateable material portion 31 can be suppressed.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting. The scope of the inventive concept is defined by thefollowing claims and their equivalents rather than by the detaileddescription of the exemplary embodiments. It shall be understood thatall modifications and embodiments conceived from the meaning and scopeof the claims and their equivalents are included in the scope of theinventive concept.

We claim:
 1. A plating method, comprising: preparing a substrate havinga non-plateable material portion and a plateable material portion formedon a surface thereof; imparting a catalyst selectively to the plateablematerial portion by supplying a catalyst solution onto the substrate;and forming a plating layer selectively on the plateable materialportion by supplying a plating liquid onto the substrate, wherein a pHof the catalyst solution is previously adjusted such that the platinglayer is suppressed from being precipitated on the non-plateablematerial portion while being facilitated to be precipitated on theplateable material portion.
 2. The plating method of claim 1, whereinthe non-plateable material portion is made of SiO₂ as a main component,the plateable material portion is made of SiN as a main component, andthe pH falls within a range from 2 to
 3. 3. The plating method of claim1, wherein the substrate includes a base member made of the plateablematerial portion and a core member which is protruded from the basemember and is made of the non-plateable material portion.
 4. A platingapparatus, comprising: a substrate holding unit configured to hold asubstrate having a plateable material portion and a non-plateablematerial portion on a surface thereof; a catalyst imparting unitconfigured to impart a catalyst selectively to the plateable materialportion by supplying a catalyst solution onto the substrate; and aplating liquid supply unit configured to form a plating layerselectively on the plateable material portion by supplying a platingliquid onto the substrate, wherein a pH of the catalyst solution ispreviously adjusted such that the plating layer is suppressed from beingprecipitated on the non-plateable material portion while beingfacilitated to be precipitated on the plateable material portion.
 5. Theplating apparatus of claim 4, wherein the non-plateable material portionis made of SiO₂ as a main component, the plateable material portion ismade of SiN as a main component, and the pH falls within a range from 2to
 3. 6. A computer-readable recording medium having stored thereoncomputer-executable instructions that, in response to execution, cause aplating apparatus to perform a plating method as claimed in claim 1.